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2 years ago

How much heat, in joules, is required to warm a metal disc from 19 °C to 33 °C? The

Chemistry

1 answer:

zalisa [80]2 years ago

3 0

Answer:

Q = 96.6 j

Explanation:

Given data:

Heat required = ?

Initial temperature = 19°C

Final temperature = 33°C

Mass of disc = 3.0 g

Specific heat capacity = 2.3 J/g.°C

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 33°C - 19°C

ΔT = 14°C

Q = 3.0 g×2.3 J/g.°C × 14°C

Q = 96.6 j

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A) explain why caesium is more reactive than potassium.

Kamila [148]

Answer:

Explanation:

(a) Firstly, caesium abd potassium are both in Group 1 of the periodic table. Group 1 metals (also called alkali metals) are the most reactive metals of the periodic table. Caesium is more reactive than Potassium because it has a higher electropositivity than Potassium. Electropositivity is the tendency of a metal to donate electron(s) to form a cation. Electropositivity increases down the group; this is because it is easier for atoms to loose electrons on the outermost shell that are far away from the central nucleus as against atoms whose outermost electrons are closer to the central nucleus. Thus, the more "bulky" an atom is, the farther it's outermost electrons (valence electrons) get from the central nucleus and the easier it is to lose the outermost electron(s). And the easier it is for the valence electron(s) to be removed, the more reactive the atom would be and vice-versa.

Caesium is more reactive than potassium because it is more bulky than potassium, with an atomic number of 55, while potassium has an atomic number of 19.

NOTE: The closer an electron is to the nucleus, the more difficult it is to be removed from it's shell.

(b) i. Formula for Caesium Nitrate:

Symbol for Caesium is Cs and Nitrate is NO₃⁻.

Cs⁺ + NO₃⁻ ↔ CsNO₃

Formula for Caesium Nitrate is CsNO₃

ii. Formula for Caesium sulphate

Symbol for caesium is Cs and Sulphate is SO₄²⁻

Cs⁺ + SO₄²⁻ ↔ Cs₂SO₄

Formula for Caesium sulphate is Cs₂SO₄

NOTE: When writing the formulae, the charges would be exchanged to form the subscript as seen on the product sides above.

7 0

2 years ago

What is the full meaning of DR.HERC.

n200080 [17]

Answer:

It is

D- DEFINE the problem

R-RESEARCH on the problem

H- Carry out a HYPOTHESIS

E- carry out an EXPERIMENT.

R-Analyse the RESULT

C-summarise the CONCLUSION.

Explanation:

Hope it helps.

5 0

2 years ago

A gas has a volume of 490. mL at a temperature of -35.0 degrees C. What volume would the gas occupy at 42.0 degrees Celsius? Ple

11Alexandr11 [23.1K]

Answer:

V₂ = 648.53 mL

Explanation:

Given data:

Initial volume of gas = 490. mL

Initial temperature = -35°C (-35 + 273 = 238 k)

Final temperature = 42°C = (42+273 = 315 k)

Final volume = ?

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

V₂ = V₁T₂/T₁

V₂ = 490 mL × 315 K / 238 k

V₂ = 154350 mL.K / 238 K

V₂ = 648.53 mL

8 0

2 years ago

Explain why the lattice energy of CaSe is approximately 4 times as large as that of KBr. Check all that apply. Check all that ap

Elza [17]

Answer:

According to Coulomb’s law, the Ca and Se ions have 4 times the attractive force (2+ × 2-) than that of the K and Br ions (1+ × 1-).

Explanation:

From Coulomb's law, the attractive force between calcium and selenium ions is four times the attractive force between potassium and bromide ions.

This has something to do with size and magnitude of charge. Calcium ions and selenide ions are smaller and both carry greater charge magnitude than potassium and bromide ions. This paves way for greater electrostatic attraction between them when the distance of the charges apart is minimal. Hence a greater lattice energy.

4 0

2 years ago

How do you prepare 1 liter of a 0.5 molar glucose solution?

riadik2000 [5.3K]

Answer: 90 grams

0.5 molar of glucose means 0.5mole glucose for 1 liter of water. Since we want to made 1L of solution, then the amount of glucose needed is: 0.5mole/l x 1l= = 0.5mole

Glucose molecular weight is 180, then 0,5 mol of glucose is= 0.5mole x 180 grams/mole= 90 grams.

6 0

2 years ago